What does this research mean for the field?

Alpha-receptor-mediated coronary vascular tone is negligible at rest in both denervated and normally innervated human hearts, and the increase in vascular resistance observed after nonselective beta-blockade is due to direct beta-2 vascular effects. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

What question did this study set out to answer?

To explore basal adrenergic influences on coronary circulation in humans, particularly after cardiac transplantation.

April 1, 1989CirculationOpen Access

Effects of regional alpha- and beta-blockade on resting and hyperemic coronary blood flow in conscious, unstressed humans.

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Why the study?

Does regional alpha- and beta-blockade alter resting and hyperemic coronary blood flow in conscious humans with denervated or innervated hearts?

Key Points

To explore basal adrenergic influences on coronary circulation in humans, particularly after cardiac transplantation.
Studied 56 denervated heart transplant patients and 19 innervated patients with normal coronary arteries.
Measured coronary blood flow velocity using a 3F intracoronary Doppler catheter during cardiac catheterization.
Conducted alpha- and beta-blockade using phentolamine and propranolol/metoprolol, respectively.
After alpha-blockade, mean arterial pressure decreased significantly in both groups (denervated: -5.8%, innervated: -12.6%, p<0.05).
Coronary flow velocity reductions were noted (denervated: -8.2%, innervated: -9.2%).
Nonselective beta-blockade increased vascular resistance (innervated: +15.4%, denervated: +10.2%).

Structured PICO

Does regional alpha- and beta-blockade alter resting and hyperemic coronary blood flow in conscious humans with denervated or innervated hearts?

Population

75 conscious, unstressed humans, comprising 56 patients with denervated hearts after cardiac transplantation and 19 normally innervated patients with angiographically normal coronary arteries.

Intervention

Regional sympathetic blockade via intracoronary injections of phentolamine (3 mg, alpha-blockade), propranolol (2 mg, nonselective beta-blockade), or metoprolol (3 mg, selective beta1-blockade).

Comparator

Baseline measurements prior to pharmacological blockade.

Outcome

Changes in coronary blood flow velocity, mean arterial pressure, and coronary vascular resistance.surrogate

This physiological study demonstrates that alpha-receptor-mediated coronary vascular tone is negligible at rest, and increased vascular resistance following nonselective beta-blockade is driven by direct beta-2 vascular effects.

Discussion

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Implication

Supports negligible resting coronary alpha-tone and beta2-driven resistance increases; hypothesis-generating for beta-blocker effects in denervated hearts.

Cite This Study

Hodgson et al. (1989) studied this question.

synapsesocial.com/papers/6a1c837594dbf6307b2fdce9 https://doi.org/10.1161/01.cir.79.4.797

Topics

Heart transplantation

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Implication

Supports negligible resting coronary alpha-tone and beta2-driven resistance increases; hypothesis-generating for beta-blocker effects in denervated hearts.

Effects of regional alpha- and beta-blockade on resting and hyperemic coronary blood flow in conscious, unstressed humans.

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Topics

Effects of regional alpha- and beta-blockade on resting and hyperemic coronary blood flow in conscious, unstressed humans.

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Also Consider

Topics

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